The blood glucose meter is an important instrument to measure the glucose containing information in the blood of a human body or an animal body, especially for one suffering from diabetes. For diabetics, they have to measure the blood glucose content in their bodies from time to time so that the blood glucose content may be observed and controlled. A non-invasive blood glucose meter helps to avoid the painful blood removing procedure and is welcome by the doctors and the patents.
In the conventional art, a non-invasive glucose meter measures the blood glucose content by analyzing the near-infrared (near-IR) absorption spectra of the blood. However, due to the drifting in the discrete-type infrared sensor, as used in the conventional blood glucose meter, the near-IR absorption spectrum of the glucose can be deviated. In order to obtain stable blood glucose information, it is necessary to use a single-source-single-detector in the blood glucose meter.
In 1988, Schlager disclosed a non-dispersive differential two-beam energy absorption spectra measurement device (U.S. Pat. No. 4,882,492). In 1990 Rosenthal et al. disclosed a non-invasive measurement of blood glucose which uses a near-IR light emit device (LED) and a photo diode to non-invasively measure the blood glucose content in a human body by analyzing the near-IR transmission and absorption spectra of the blood (U.S. Pat. Nos. 5,086,229 and 5,077,476). In 1993, Yang disclosed a blood glucose meter which detects wave lengths from 1.3 to 1.8 .mu.m. (U.S. Pat. No. 5,267,152). The above patents pertained to measurement of blood glucose contents by analyzing the absorption or scattering spectra of near-IR spots.
In 1992 and 1993, Myron Block disclosed a method to measure the blood glucose content. In this invention, a near-IR filter is used. (U.S. Pat. Nos. 5,321,265 and 5,434,412). In 1995 Myron Block further disclosed an assembly of multiple Michilson interferometers. Under the architecture of this patent, a wide-band light source is used.
In order to obtain multi-band energy absorption spectra, a conventional blood glucose meter comprises an assembly of multiple laser diodes and photodiodes. Decay in illumination and drifting in light color, however, are noted in the laser diodes under strong illumination. This harms the correctness of the measurement. Moreover, as discrete components are used in the conventional art, different magnitudes shall be applied in different bands of the absorption spectrum. This makes calibration complicated. Although Myron Block disclosed a feasible proposal, the original color sensing components used in his invention are always not stable which made it difficult to be commercialized.
It is thus a need in the industry to provide a novel non-invasive blood glucose meter which is compact, can measure the energy absorption of blood from the extrusive portions of human body and can avoid the drawbacks of the conventional discrete components while a uniformed magnitude can be applied to all bands in the absorption spectrum.